We are undertaking studies to obtain data to confirm or refute the hypothesis that breast self-examination can lead to earlier breast cancer detection and decreased breast cancer mortality. We are collecting data on all breast cancer patients in the State of Vermont with breast cancer newly diagnosed since 1 July 1975 and we are determining the frequency of breast self-examination performance prior to breast cancer detection, the clinical tumor-node-metastases stage, the pathologic stage and the mortality rates. In addition, we are attempting to obtain data on the clinical and pathologic stage of breast cancer for women taught breast self-examination during a state-wide campaign during the years 1975-1978 and will attempt to compare the data in those patients to the data obtained on the general population of Vermont women.